JANUARY 5, 1939 FLIGHT. 3
ments. The result is that, although in point of years
the gyroplane is already old, its development, technically
speaking, is just about to begin in earnest. Only by
concerted action can the process of development be
speeded-up, and the steps taken by the American
Government should help materially. The question is,
what is our own Air Ministry going to do about it?
Speed with Safety
RECENT developments appear to show that we may be approaching a period of renewed activity in helicopter experiments. The Focke-Achgelis F.61
twin-rotor machine, so ably demonstrated by Fraulein
Hannah Reitsch last year, served to focus attention on
the helicopter. Dr. Focke concentrated on showing
that controllability—the most difficult of the helicopter
problems—could be attained. It is scarcely to be be
lieved, however, that he regards the F.61 as anything
but a stepping-stone towards something better, some
thing more advanced and with a better aircraft per
formance.
Speed is not easily obtained with two rotors. No
matter how one arranges the rotor-carrying outriggers,
they are bound to offer a considerable amount of un
desirable drag. Other designers, among them Mr. Raoul
Hafner, whose account of his recent participation in the
First Rotating-wing Meeting in America is published this
week, believe that sufficient controllability can be
obtained with a single high-speed rotor. Should that
be the case, and there is good reason for thinking that
it is the case, then the prospects of a helicopter with a
top speed comparable with that of the equivalent fixed-
wing aeroplane are much better.
The speed range of such a helicopter will, of course,
be very much greater than that of the best fixed-wing
aeroplane in that the minimum speed is zero. And with
a single rotor the possibility exists of avoiding excres
cences which would otherwise tend to spoil the perform
ance. Mr. Hafner has ideas about countering rotor
torque reaction, and others have sought different ways
of achieving the same object. So altogether it looks
likely that 1939 will be a helicopter year.
The Lisbon Service
THE London-Lisbon air mail service, which was to have started last Monday, has been temporarily postponed. This change of plan is semi-officially
explained as being the result of difficulties over the final
arrangements with the Portuguese authorities. Disre
garding these (whatever they may be), it is certainly a
fact that no D/F facilities have so far been available
at Cintra aerodrome, Lisbon, and it seems, on the face
of it, to be somewhat optimistic to be making an attempt
to run a regular service without them.
The only possible method of reaching Lisbon in such
circumstances and in bad weather is to dead-reckon ovei
the clouds until it is quite certain that the Lockheed 14
is over the Atlantic and then to come dawn to look at
the sea before flying on an easterly course to find the
mouth of the Tagus and follow low ground to the aero
drome. This, in any case, is much too small, and only
one really good bad-weather approach seems to be avail
able. Recently, too, floods have added to the general
discomfiture of all concerned.
Remembering that even a mail service should, as
nearly as possible, be 100 per cent, reliable, it is, per
haps, just as well that the regular service has been'
postponed. Possibly the reason for this is, in fact, that
the navigational facilities over the last part of the route
are more than inadequate. With present-day types it
is suicidal to run a service without realty complete ter
minal facilities—and, at the most optimistic estimate,
Lisbon is certainly poorly equipped by modern standards
for serious air arrivals.
" Flight " photograph.
FLAMINGO FLEDGED : Seen here on one of its early test-flights, the De Havilland Flamingo presents a picture of beauty that
belies its somewhat ungraceful name. Other ground and air photographs appear on pages 15 and 16.